﻿<p>The physical quantity, <em>IfcPhysicalSimpleQuantity</em>, is an entity that holds a single quantity measure value (as defined at the subtypes of <em>IfcPhysicalSimpleQuantity</em>) together with a semantic definition of the usage for the measure value.</p> 

<blockquote class="example">
EXAMPLE&nbsp; An element, like a wall, may have several area measures, like footprint area, left wall face area, right wall face area. These areas would be given by three instances of the area quantity subtype, with different <em>Name</em> string values.
</blockquote>

<p>A section "Quantity Use Definition" at individual entities as subtypes of <em>IfcBuildingElement</em> gives guidance to the usage of the <em>Name</em> attribute to characterize the individual quantities. If the <em>Unit</em> attribute is given, the value attribute (introduced at the level of subtypes of <em>IfcPhysicalSimpleQuantity</em>) are given as quantities of this unit, otherwise the global unit definitions (given by <em>IfcUnitAssignment</em>) are used.</p>

<blockquote class="history"> 
HISTORY&nbsp; New entity in IFC2x2 Addendum 1.
</blockquote>

<blockquote class="change-ifc2x2"> 
IFC2x2 ADDENDUM 1 CHANGE&nbsp; The abstract entity <em>IfcPhysicalSimpleQuantity</em> has been added. Upward compatibility for file based exchange is guaranteed.
</blockquote>